What Is One Major Reason Why Dangerous New Infectious Diseases

Multiple Choice

What is one major reason why dangerous new infectious diseases have emerged in recent years?

A) Several stands of experimental viruses have not been adequately controlled in laboratory settings.
B) Some countries have already begun to experiment with germ warfare.
C) Certain infectious viruses which have their origin in space have landed on earth as falling space debris.
D) The overuse of antibiotics has meant that some infectious diseases have become resistant to their effects.